System of motor control.



Patented nec. la, |900.

No. 663,95l.

A. H. ARMSTRONG.

SYSTEM OF MOTOR CONTROL.

(Application med occ. 6, 1900.;

No Modal.)

3 S stig-Sheet .m .mi

my mm mm, am

Wime-s M No. 663,95l. A Patented Deb. is, 1900. A. H. ARMSTRONG.

SYSTEM F MOTOR CONTROL.

V (Application led Oct. 6, 1900A inventor Albert H frmstmng 3 Sheets-She@ 3.

(No Model.)

UNITED STATES PATENT OFFICE.-

ALRERT n. ARMSTRONG, OE scHENEoTAnY, NEW YORK, AssIcNOR To THE GENERAL ELEOTRTO COMPANY, OE NEw YORK.

SYSTEM OF MOTOR CONTROL.

SPECIFICATION forming part of Letters Patent No. 663,951, dated December 18, 1900.

Application led October 6, 1900. Serial No. 32,258. (No model To all whom t T11/Ly concern:

Be it known that I, ALBERT H.ARMsTRoNc,a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Systems of Motor Control, (Case No. 1,75S,) ot which the following is a specification.

My invention relates to a system of motor control, and has for its main object to provide a system for the individual control of a plurality of induction-motor equipments operated from an alternating-current source. It is not, however, limited to an alternatingcurrent system, since certain ot its features are applicable as well in a direct-current system. Moreover, the entire system of control may be utilized, irrespective of the character of the source of supply for the motors, if some means is provided for supplying mnltiphase current to the actuating devices of the motorcontrollers.

The system which I have devised is especiallydesigned for a train-control system, and comprises the general features which characterize direct-current train-control systemsnamely, motor-controllers on one or more motor-cars controlled vfrom a master-controller located at any desired point on the train.

My invention will be understood by reference to the following' description, taken in connection with the accompanying drawings, while its scope will be pointed out in the appended claims.

In the drawings, Figure I is a diagram showing a train of cars to which my invention may be applied. Fig. 2 is a diagram illustrating the apparatus and circuit connections for a single car of a train arranged accordingto my invention. Fig. 3 isa diagram illustrating a modification of the sytem shown in Fig. 2. Figs. e and 5 are end and side views, respectively, in partial cross-section of one of the elements of the motor-controllers diagrammatically illustrated in Figs. 2 and 3; and Figs. 6 and 7 are end and side views, respectively, of the reversing-switch shown in diagram in Figs. 2 and 3.

Referring` iirst to Fig. l, L, L2, and L3 indicate three cars united to form a train. Each of the cars is provided at each end with a master-controller M, connected to a system of conductors extending from one end to the other of the train. Each car is also provided with a controller B, arranged to control the circuit connections of the motors M and M2. The actuating devices ot all of the motor-controllers are operatively connected to the systern of conductors to which the master-controllers are connected.

In Fig. 2 I have shown in diagram the circuit connections according` to my invention for one of the cars shown in Fig. 1, it being of course understood that the train may comprise any desired number of cars, onl y a part of which need be provided with propelling.

motors, and that the circuit connections about to be described are required only on those cars,which are provided with motors,the other cars of the train, unless they are mere trailers, being equipped with the system of train-conductors only Or with train-conductors and master-controllers. In Fig. 2 the numerals 2 to S, inclusive, represent a system of traincondnctors, each of the'said conductors being provided at each end with a terminal t, by means of which it may be connected to a corresponding conductor on the adjacent cars. At each end of this system ol' conductors is provided a master-controller M, the one at the right being shown in partial outline only, while the one at the left is shown with its contacts developed on a plane surface, as is customary in diagrammatically illustrating such structn res. Each master-controller comprises a switch (l Vfor controlling the resistance connections of the propelling-motors and a switch R S for controlling the direction of flow ot' current through the windings of said motors.

rlhe motor-controller is shown at B and comprises a plurality of contact devices a' to a, inclusive, and a, the said contact devices being actuated by induction-motors A to A, inclusive, and AM, the rotating members of which are suitably connected to the contact devices and the fixed members of: which are supplied with multiphase currents in a manner hereinafter to be described. The contact device a controls the connection between the prim ary circuits ot' the propelling-motors and the source and is maintained in its closed position as long as the switch C of the mastercontrollcr is in any one of its Operative posi- IOO tions. The contact devices cto a, inclusive, control, in the case of the particular type of propellingmotors shown, the resistance of the secondary circuits of the motors and are successively closed as the switch C of the mastercontrolleris moved to itsinal position. Each of the contact devices a' to a comprises two sets of fixed terminals ff andf2f3 and two movable contacts d and e, arranged to be brought into engagement with said terminals, so as to complete circuits through the same.

The system which l have illustrated is designed to be operated from a three phase source, the propelling-motors M and M2 being supplied with current through three circuits, two of which are connected to the trolley-shoes T and T2 and the other to a permanent ground connection which may be completed through the carwheels and rails. Since in order to open-circuit a three-phase system it is only necessary to open the circuit of two of the three leads, I have provided switches only in those leads to which the trolley-shoes are connected, the terminals fand f and the contact d of the contact device a constituting the switch in the lead l and the terminals f2 and f3 and the contact c of the 1same contact device constituting` the switch in the lead Il. The leads land II are connected to the contacts of a reversing-switch am, operated by the induction-motor A, and from the reversing-switch conductors HI and IV lead to two of the terminals of the propelling-motors, the third terminal being connected to ground through the conductor V. The reversing-switch am is similar in its general construction to each ofthe devices a to a, save that it has two operative positions and therefore four sets ot' terminals in the motorcircuits instead of the two sets with which the main contactdevices are provided. There are also four additional sets of terminals in eluded in the operating-circuits between the reversing-switch-actuating motors and the master-controller, the function of which will be hereinafter described.

The secondary or induced windings of the propelling-motors are connected through collecting-rings to the conductors V, VI, and VII, between which the several sections of a resist-ance R are permanently connected. Other resistances R2, R3, R4, and R5 are arranged to be connected in multiple with resistance R as the contact devices ot the motor-controller are actuated, and in the final position of the controller all the resistanccs in circuit with the induced windings are shortcircuited by a connection S.

The actuating-motors of the motor-controllers are supplied with current from the main source preferably through a tensionreducing transformer T. This transformer has two of the terminals of its primary circuit con neet-ed to the trolley-shoes T and T', the third terminal being connected to ground. One of the secondary terminals is connected to ground through the conductor l0 in comm on with one of the terminals ot' each of the motors A to AG and A, and the connections between the other secondary terminals and the other terminals of the controller-actuating motors are controlled through the switches ofthe mastercontrollers. These two terminals of the transformer secondary areA connected by means ot conductors 9 and l to the Iixed contacts 9 and l of the switch C and to the fixed contacts 9 and l" of the switch R S of the master-controller. The remaining fixed contacts of the switch C are connected each to a corresponding train-conductor, and the remaining fixed contacts of the switch R S are connected through conductors l] to 14 to certain auxiliary terminals of the reversing-switch and through them (until the switch has been operated) to the train-conductors 5 and (i, to which two terminals of the reversing-switch actuating motors A14 are connected.

Supposing the parts to be in the positions illustrated in Fig. 2, the controlling-circuits will be open at the contacts oli' the switch C of the master-controller and the primary or inducing circuits of the propellingmotors will be open at the terminals of the contact device a. Il nowthe controlling-switch C of the master-controller is moved into its iirst operative position so as to bring the movable contacts c into engagement with the fixed contacts l', 2', 8, and 9', current from the secondary of the three-phase transformer will iiow through the conductors l, 9, and lO as follows: from conductor l to the contact 1, thence by way ol the cross-connected contacts c to the contact 2 and conductor 2 of the train system, from conductor 9 to the contact 9, thence by way of cross-connected contacts c to the contact 8' and conductor 8 ot' the train system, and from conductor l0 to the permanent ground connection. Since the three terminals of the motor A on each of the cars of the train are connected to the train-conductors 2 and 8 and to the ground connection lO, the currentsupplied in the first position ot' the master-controller will actuate the rotatable member of the motors A to close the contact devices a As soon as these contact devices are closed current will tlow from the trolley-shoes 'll' and T2 on each car th rough the contacts of the contact device a to the conductors l and Il, and thence through the contacts of the reversing-switch to the cond uctors HI and lV and to two of the terminals ot the inducing windings ofthe motors M" M2, the third terminal of each ot these windings being connected to ground through the conductor V. The motors M and M2 will now start in operation, but will run at low speed, because ot' the fact that the large resistance R is included in the circuit of their induced elements. lt has already been stated that one terminal of each ot' the motors A to AG is permanently connected to ground. It will further be noted that another terminal of each motor is connected to the train-conductor 2. As soon, therefore, as the switch C has been IOO IIO

moved into its iirstvoperative position to actuate the motor A/ current will be supplied from one of the windings of the three-phasetransformer secondary to a portion of the winding of each of the motors A2 to A5; but since this current is single phase the said motors will not be actuated. As soon, however, as the third terminal of each motor is connected tothe third terminal of the transformersecondary it will be supplied with three-phasecurrents, and will therefore be actuated to close the corresponding contact device. The third terminal of each of the motors is connected to one of the train-conductors 3 7, and these train -conductors as the mastercontroller is operated are successively connected to the conductor 9, leading` to the third terminalof the transformer secondary. With the connections shown the current for actuating all the controller-motors is obtained from a single transformer, but the transformers on the several cars may be connected in multiple through conductors of the train system. When the main controlling-switch of the master-controller is moved into its second fore to reduce the value of the resistance in circuit with the induced members of the propelling-motors. In the third position ofthe master-controller the circuit connections already referred to will be maintained and in addition a new circuit will be closed from the conductor 9 through the contacts 9' and e to the conductor 4 of the train system. The motor A3 will then be caused to actuate its contact device a3 to further reduce the resistance in the circuit of the induced members of the propelling-motors by connectingin the resistance R3. In the subsequent positions of the master-controller the remaining contact devices will be actuated and in the last position 6 6 the contact device as will shortcircuit all the resistances R to R5, inclusive, thereby cutting out all the resistance in the induced circuits of the driving-motors. This is the running position of the controller.

The connections between the actuatingmotors for the reversing-switches on the several cars and the master-controller reversingswitch are so arranged that the said reversingswitches may be actuated without increasing the number of train -conductors above that required to operate the resistancecontact devices of the controller. This arrangement is rendered possible by reason of the fact that the reversing-switch is operated only when the switch C is in its ofi' position. The terminals of the motors A14 on the several cars of the train are connected to the trainconductors 5 and 6, and these conductors are connected to the conductors 9 and 1 through auxiliary contact devices operated by that one of the motors A14 which is on the same car with the master-controller from which the train is for the time being controlled. The reversing-switch motor on the car on which the master-controller is located opens the circuits between the conductors 9 and l and the train-conductors 5 and 6 as the reversingswitch is operated, and therefore leaves the said train-conductors after the reversingswitches have been operated entirely disconneet-ed from the actuating-circuits. With the reversing-switch R S ofthe master-controller in the position shown in thedrawings the contact device d of the main reversing-switch will occupy the position shown, with its movable contacts engaging the fixed terminals on the left7 so that the conductor I is connected through one of said contacts to the conductor IV and the conductor II through another of the contacts to the conductor III. If now the switch It S is moved so as to carry the movable contacts d out of engagement with the fixed cont-acts and to bring the movable contacts b into engagement with the same, circuits for the motors A14 will be closed as follows: from conductor 9 to fixed contact 9" of the master-controller switch R S, thence through cross-connected contacts b to the fixed contact l2, thence by way of conductor l2 through one of the auxiliary contacts of the contact device am to conductor 6 of the train system, and thence to one of the terminals of each ol' the motors A14, from conductor l to fixed contact l" of the switch R S, thence through cross-connected contacts l) to contact l1", and thence by way of conductor Il through another auxiliary contact of the contact device a to train-conductor 5, to which another terminal of each of the motors A11 is connected. The remaining terminal of each of the said motors is connected to the third secondary terminal of the transformer T through ground. Vhen these circuits are completed, the motors AM will be actuated and will move the contacts of the contact device am into engagement with the fixed contacts on the right. As soon as the auxiliary coni-acts on the master controller car have been moved ont of engagement with their corresponding terminals on the left the connections to the transformer secondary will be broken and the motors A14 open-circuited. At the same time the said auxiliary contacts will come into engagement with the terminals on the right, connecting the said motor-terminals and train-conductors to the ixed contacts 13" and 14 of t-he switch R S, so that the reversing-switch motors may be actuated in the reverse direction, when the switch R S is again moved to bring the movable contacts (t into engagement with the l corresponding fixed contacts.

Although two of the terminals of the mo- IOO IIO

IIS

tors A11 are permanently connected to the train-conductors 5 and 6 and the third to ground, the said motors cannot be actuated by the main controlling-switch of the mastercontroller for the reason that the two conductors 5 and 6 are never connected to different terminals of the transformer secondary, but always to the same one. In certain positions of the main controlling-switch current will be supplied to the windings of the motors A11, but it will be single-phase Current instead of three phase.

In order to prevent the operation of the switch R S unless the switch C is in its off position, and vice versa, the usual mechanical interlocking` devices will be provided. I prefer also to provide the switch C with an electromagnetic lock connected in circuit with the switch R S and operating to prevent movement oi' the switch C unless all the main reversing-switches on the train have been properly operated. Such an electromagnetic lock for use in train-control systems has been devised by F. E. Case.

The system above described provides but four resistance-steps for the motor controllers. In many installations it will be advisable to have a greater number of steps between the oft and the ruiming positions, and in Fig. 3 I have shown how by the addition of a single train-conductor to separate the circuits of the motor A1 from the others a greatly-increased number of steps may be obtained. The system shown in Fig. 3 is in general the same as that of Fig. 2; but I have so modified the master-controller and so connected the additional actuating-motors of the motorecontroller that any one of the motors A2 and A13 may be operated without actuat ing any of those following. In order to accomplish this result, I have divided the actuating-motors into sets, one set having one terminal of each motor permanently connected to ground, a second terminal permanently connected to the train-conductor 2, and the remaining terminals connected to one of the conductorsS to 7, inclusive; another set also having' one terminal of each mot-or permanently connected to ground, a second terminalpermanently connected to train-conductor 3, and the remaining` terminals connected to one of theconductors 4t to 7, inclusive, and a third set having one terminal of each motor permanently connected to ground, a second terminal permanently connected to train-conductor 7, and the remaining terminals connected to one of the conductors 4 to 6, inclusive. The new train-conductor O has been added solely for the purpose of separating` the connections ot the motor A from the rest of the actuating-motors of the motor-controller, this being rendered necessary by the fact that since the motor A actuates the contacts which close the circuit between the source and the motors it must be maintained in its operative position throughout all the operative posi tions of the master-controller.

The operation of the system shown in Fig. 3 is as follows: When the controlling-switch of the master-controller is moved into its first operative position, the motor A' is caused to close the contacts in the main motor-circuits at d. In the second position of the mastercontroller the motor A2 is actuated to close the corresponding contact device a2. In the third position the motor A3 is actuated to close its contact device, in the fourth position the motor A1, and in the fifth position the motor A5. Up to this point as each motor is actuated the connections of the preceding motors remain unchanged. As the mastelcontroller is moved, however, from the fifth to the sixth position the motor A6 is actuated and at the same time the connection to the motor A2, through the train-conductor 3, is broken, so that the contact device actuated by this motor is returned to its off position. The connection to this motor is broken atthis point of the movement of the master-controller for the reason that the next set of motors which are to be operated from these conductors have one ot their terminals connected to the train-conductor 3 and their other free terminals connected to one of the conductors 4, 5, G, and 7, whereas up to this point in the operation of the controller one ot the terminals ofthe motors which have been actuated is connected to the trainconductor 2 and the other active terminal to one of the conductors 3, 4, 5, C, and 7. As the master-controller is moved from the sixth to the seventh operative position all of the motors of the first set, with the exception of the motor A6,are cut out of circuit and their corresponding contacts opened. Vthen the master-controller reaches its seventh operative position, the motor A1 is actuated, the motor AG maintaining' its contacts in closed position until the motor AT has been actuated and then being cut out of circuit by reason of the tact that one of the contacts c passes oft from the corresponding fixed contact 2. In the eighth position of the master-controller the motor A7 is maintained in its operative position and the motor As is operated. In the ninth position the motors A7 and A8 are maintained in operative position and the motor A9 is operated. In the tenth position the motor A10 is operated and the motor A7 cut out oi circuit, and as the master-controlleris moved from the tenth to the eleventh position the motors AS and A9 are cut out of circuit and the motor A11 actuated. In the twelfth position the motor A10 is cut out of circuit by reason of the fact that one of the contacts c passes from the corresponding fixed contact 3 and at the same time the motor A12 is actuated, while in the last, the thirteenth, position of the main controlling-switch of the mastercontroller the motor A1S is actuated and the motors A11 and A12 are maintained in their operative positions.

In the operation ci' the master-controller to make the connections above described it will be noted that when current is supplied to all IOO IIO

the terminals of certain of the motors which it is desired shall be operated certain terminals oi' other motors which are not required to be operated are connected into circuit, but never more than two terminals are connected in, so that the motors which are required to remain in their inoperative positions` are, if supplied with current at all, supplied with single-phase current flowing between two of the terminals of the motor, such current being, as is well understood, incapable of starting an ordinary induction-motor.

The construction of the several elements of the motor-controller B is shown in Figs. -lto '7, inclusive. Figs. 4E and 5 indicate the construction of each one of the contact devices cl/ to @13, inclusive, together with its actuating-motor, and Figs. 6 and 7 indicate the construction of the contact device A11, together with its actuating-motor. In Fig. 4 A indicates the motor by which the contact device is actuated, the said motor being secured in position beneath a suitable support, which may be the iioor of the car, and having its shaft s elongated and provided with an insulating-sleeve upon which are mounted two contacts b and e, which, as the motor is actuated, are caused to revolve and come into contact with ingersf to f3, inclusive, the contact d operating to close the circuit between the ingersfand f and the contact device e operating to close the circuit between the fingers j2 and f3, thus completing the circuit connections, (indicated at a to @13, inclusive, in Fig. 3.) The contacts d and e are in the construction illustrated mounted upon weighted arms, so that they are returned to the off position by gravity only; but I may also employ returning-springs, orI may make use of springs alone. The contact devices are preferably provided with a suitable arcextinguishing device, and in the embodiment illustrated in the drawings I have shown a receptacle D surrounding or inclosing the contacts and fingers and containing oil or other suitable insulating fluid. As shown in the drawings, this receptacle D is bolted to the structure beneath which the motor A is mounted and carries the bearings for the shaft s; but evidently these details of construction, as well as the form of the arcs extinguishing device, may be materially modified without departing from myinvention, which requires merely that the controller shall comprise separate sets of contacts actuated by inductionmotors. The construction illustrated in Figs. G and 7 is in general the same as that illustrated in Figs. LL and 5; but the reversingswitch is provided with four contacts instead of two. Each of these contacts consists of a cylindrical portion g, provided with sectorshaped extensions h, as shown in Fig. t', the sector-shaped extensions being arranged to contact with the iinge1sftof7,inclusive, as the shafts is moved from its extreme right-hand toits extreme left-hand position,or vice versa. Of the contact-lingers j' to f @in clusive,on each side of the reversing-switch cylindeigftofg, inclusive, are connected in the main circuit of the propelling-motors, while]UA1 to f7, inclusive, operate to make and break the connections between the source and the reversin g-switch R S of the master-controller. VVit-h theswitch in either of its operative positionsas, for example, in the position indicated in Fig. G-if the reversing-switch of the mastercontroller is moved to its other extreme position the motor A14 will be energized in such a manner as to cause the shaft s to revolve left handedly and bring the sectors 7L into contact with the sel of iingersf tof?, inclusive, at the right and out of contact with the corresponding fingers at the left. The shaft and sectors are maintained in either of the two operative positions by means of springs m, the ends of which engage lugs n, carried by the shaft. The terminal connections 7c and lt" are led from the contact-fingers to the outside of the receptacle D, so that the conductors may be conveniently attached thereto.

I have not deemed it necessary to illustrate any particular construction of the inductionmotor A, since the motor may be of any ordinary type and may have a secondary member consisting of a solid iron core or the member may be provided with a closed Winding. The motor is required to exert but little torque, since its entire load consists of the movable contacts carried by the motor-shaft,'and it may therefore be made of very small size.

l have illustrated in the drawings a threephase system only; butevidently my system may be operated from any multipliase source or even from a single-phase source if some means is provided for transforming the singlephase current into multiphase.

l/Vhat I claim as new, and desire to secure by Letters Patent of the United States, is-

l. In a train-control system, an inductionmotor equipment on one or more cars of the train, regulating resistances on each motorcar arranged to be included in circuit with the induced members ofthe motors on the said car, and means controlled from any desired point on the train for varying the resistance in circuit with said induced members.

2. In a train-control system, an inductionmotor equipment on one or more cars of the train, regulating resistances on each motorcar arranged to be included in circuit with the induced members of the motors on said car, a motor-controller on each motor-car, actuating means for said controllers, and a master-controller located at any desired point on the train,forcontrolling said actuating means.

3. In a train-control system, an inductionmotor equipment on one or more cars of the train, regulating resistances for the motors located on each motor-car, a separate controller for the resistances on each car, and a master-controller, located at a desired point on the train, for controlling the operation of all the resistance-controllers on the train.

4. In a train-control system, an inductionmotor equipment on one or more cars of the train, a resistance-controller foreach of said equipments, means for actuating each of said resistance-controllers, and a master-controller, located at any desired point on the train, for controlling the operation of said actuating means.

5. In a train-control system, a plurality of cars equipped with induction-motors, resistances on each of'said cars arranged to be included in circuit with the induced members of said motors,controllers for said resistances, actuating means for said controllers constructed and arranged to be operated from an altern atin g-current source,and a master-controller, located at any desired point on the train, for controlling` the connections between a source of alternating-current supply and the said actuating means.

(i. In a system of motor controha controller com prising a plurality of separately-actuated cont-act devices and an actuating device Vfor each of said contact devices comprising an induced member operatively connected to the contact device and an inducing member arranged to be supplied with current from an alternating-current source.

7. In a system of motor controhacontroller comprising a plurality of separately-actuated contact devices, and an induction-motor operatively connected to each of said contact devicesf 8. In a system of motor control,a controller comprising a plurality of separately-actuated contact devices, an induction-motor for operating each of said contact devices, a source of altern ating current,and a master-controller constructed and arranged to connect the inducing member of each of said motors to said source.

9. In combination, a controllercomprising a plurality of separately-actuated contact devices, an induction-motor operatively connected to each of said contact devices, a source of alternating current, and a master controllerfor controlling the connection between said motors and said source.

10. In a motor-control system, a controller comprising separately-actuated contactdevices, multiphase motors for actuating said contact devices, a source of multiphase current, common connections between certain of the terminals of each motor and the source, separate connections between the remaining motor-terminals and said source, and a master-controller for controlling the latter connections.

1l. In a motor-control syst-em, a plurality of conductors, controller-actuating devices connected to said conductors, a separate de- Vice for actuating the reversing-switch connected to the same conductors, and means whereby the main controlling-contacts may be operated Without effecting the operation of the reversing` switch contacts and vice versa.

l2. In a motor-control system, a plurality of conductors, controlleractuating means connected to said conductors, a separate means for actuating the reversing-switch connected to certain of said conductors, means for closing a circuit. from the source of supply to the conductors to which the reversingswitch-actuating means is connected, and means operated by the reversing-switch for opening said circuit.

13. In a motor-control system, a plurality of conductors, controlleractuating` means connected to said conductors, a separate means for actuating the reversing-switch connected to the same conductors, a master-controller comprising a controlling` and a reversing switch interposed between the source of supply and the said conductors, and means operated by the motor-reversing switch for opening the circuit between the master-reversing switch and the system oi2 conductors.

1st. In a motor-control system, a system of conductors, actuating devices for the main controller-contacts connected to said conductors, and an actuating device for the reversing-switch contacts connected to certain ol the conductors to which the other actuating devices are connected.

15. In a train-control system, a motor-controller comprising sepalately-actuated contact devices, multiphase motors for actuating said contact devices, a source of multiphase current, common connections between certain of the terminals ot' each motor and the source, a system of train-conductors less in number than the number of motors to which the remaining terminals are connected and a master -coutroller arranged to successively connect the multiphase motors to the source.

16. In a train-control system, a motor-controller comprising separately-actuated contact devices, a multiphase motor for actuating each of said devices, said motors being connected in a plurality of sets to a system of train-conductors less in number than the number of motors, a source of multiphase current, and a master-controller interposed between said system of conductors and said source, and arranged to supply current to actuate the motors ot' 011e set without causing` the operation of any of the motors in the other sets.

17. In a train-control system, reversingswitch contacts ou each of the motor-cars of the train, actuating devices for said contacts, train-conductors to which said actuating devices are connected, a master-reversing switch connected to supply current from a suitable source to said conductors, andanxiliary contacts actuated by one of thereversin g-s witches for opening the circuit between the masterrcversing switch and the train-conductors In witness whereof I have hereunto set my hand this 5th day of October, 1900.

ALBERT II. ARMSTRONG. lVitnesses:

BENJAMIN B. HULL, MARGARET E. WooLLnY.

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